Donchian Channels

A channel built from the highest high and lowest low over a chosen lookback period.

What it is

Donchian Channels, developed by trader Richard Donchian, are a three-line indicator plotted directly on the price chart. The upper band is the highest high over the last N bars, the lower band is the lowest low over the last N bars, and the middle line is the average of those two values. A common default is 20 periods. The channel simply visualizes the recent trading range and where price sits within it. It is educational information about past price extremes, not a prediction of future movement, and no indicator can remove the risk of loss in trading.

How it works

For each bar, the indicator looks back over a fixed number of bars (for example 20) and records two things: the single highest high and the single lowest low within that window. Those become the upper and lower bands. The middle line is just the midpoint between them. As new bars form, the window slides forward, so the bands step up or down only when a new extreme high or low enters or leaves the lookback. Because the bands track recent highs and lows rather than a smoothed average, they tend to stay flat during quiet ranges and shift quickly when price prints a new extreme.

How traders read it

• Traders often read price touching or pushing the upper band as the market trading at its highest level of the lookback window, and the lower band as its lowest.
• A common interpretation is that the bands mark the current range boundaries; some traders watch for price moving beyond a prior band as a possible sign of expansion out of that range, though this is descriptive, not a forecast.
• The width between the bands is sometimes read as a rough gauge of recent range or volatility — a narrow channel reflects a tight range, a wide one reflects larger swings.
• The middle line is frequently used as a reference for the range midpoint, with price above or below it describing which half of the recent range the market is in.
• Flat, parallel bands are often interpreted as range-bound conditions, while bands that step steadily higher or lower are read as a one-directional move.
• No indicator is predictive: the bands describe what price has already done, and all trading carries risk of loss.

Common settings

A lookback period of 20 bars is the most widely cited default. Shorter settings such as 10 react faster to recent extremes; longer settings such as 50 or 55 (a length associated with classic trend-following systems) produce a wider, slower channel. Applied to the price chart as an overlay.

Strengths

• Simple and fully transparent — the bands are just the highest high and lowest low, with no smoothing parameters to tune.
• Makes the current trading range and recent extremes easy to see at a glance.
• Works on any market or timeframe because it only needs price highs and lows.
• The lookback length is the single adjustable input, making the behavior easy to reason about.

Pitfalls to watch

• The bands are backward-looking by construction — they only update after a new high or low has already printed, so they inherently lag the move that created them.
• In choppy, sideways markets, price can repeatedly poke beyond a band and reverse, which traders often describe as false breakouts or whipsaws.
• A very short lookback makes the channel react to almost every swing (noisy); a very long one makes it slow and wide. The chosen period heavily shapes what you see.
• Because the upper and lower bands depend only on the most extreme bar in the window, a single spike or wick can move a band sharply and distort the picture.
• The channel says nothing about direction, momentum, or whether a level will hold — reading a touch as a signal to act would be a misuse; it is descriptive only.

Pine v6 example

//@version=6
indicator("Donchian Channels", overlay = true)

length = input.int(20, "Lookback", minval = 1)

upper = ta.highest(high, length)
lower = ta.lowest(low, length)
basis = math.avg(upper, lower)

u = plot(upper, "Upper", color = color.teal)
l = plot(lower, "Lower", color = color.teal)
plot(basis, "Basis", color = color.gray)
fill(u, l, color = color.new(color.teal, 90))

Pro tip: Watch the lookback length deliberately. Because each band is set by the single most extreme bar in the window, a wick or one-off spike can pin a band for the full lookback. Comparing the channel against the actual candles helps you tell a genuine range shift from a one-bar outlier. This is for education only and is not advice to act on.

Educational only — not financial advice, not a recommendation to trade. No indicator is predictive; trading involves substantial risk of loss.